Already known in accordance with French Patent 1,329,624 is an arrangement where the one of the two constructional units is arranged in stationary fashion and forming, for example, the stator of an electric generator, while the other constructional unit is arranged on the bearing of a traversing shaft, for example the generator shaft. The constructional unit arranged on the generator shaft is prestressed axially, in fashion of a full surface contact of the common cone bearing surface against the stator, by a group of locking pawls distributed over the circumference of the stator and prestressed radially, inwardly. Achieved by this means is that the shearing pins arranged between the two constructional units will not be loaded by radial oscillations between the two constructional units and break, in undesired fashion, before reaching a preselected maximum moment of rotation. Rather, relative to the shearing pins, loading occurs exclusively by tangential shearing action. In the case of the known arrangement, exceeding the maximum moment of rotation can then occur when the shaft bearing, on which one of the two constructional units is supported, locks. If such a case of overloading does occur, then the constructional unit supported on the shaft is pushed away axially from the stator by several hydraulic positioning members in the stator, arranged in distributed fashion over its circumference, so that a radial play then arises at the common cone bearing surface, and the constructional unit that is supported on the shaft having a second cone surface is, at the same time, brought into engagement with a second cone surface of the stator, whereby, as a result instead of a blocked and/or destroyed bearing, a second redundancy bearing is set into operation. Transfer from the destroyed bearing to the redundant bearing is accomplished during a single revolution of the shaft by actuation of an electromagnetic switch. The overall arrangement requires, compared to the diameter, relatively great axial dimensions.
Known from U.S. Pat. No. 4,186,570 is a shearing pin moment of rotation limiting arrangement, in a rigid shaft coupling, that comprises two approximately coaxial coupling halves, in a stationary arrangement, each one on an associated shaft journal. Arranged in distributed fashion over the circumference of the two coupling halves are several shearing pins that are braced inside of each of the two coupling halves by means of slotted cone bushings. Oscillatory loadings of the shearing pins as a result of mutual vibrations of the two shaft journals are also avoided with this arrangement, so that the shearing pins are loaded exclusively by tangential shearing forces. In the event of a reaction of the shearing pins, which means a shearing off of all shearing pins, these latter are to be removed individually from the two coupling halves and a new set of shearing pins is to be installed and carefully fixed by means of the slotted cone bushings. This requires a considerable expenditure of time. Furthermore, there also exists the danger that the screws to used to fix the shearing pins will become loose in operation, whereby reliability of reaction at the preselected maximum moment of rotation would be reduced.
Also known are torsionally elastic shaft couplings that comprise two approximately coaxial coupling halves in a stationary arrangement, each one on an associated shaft journal. Each one of the coupling halves displays, distributed over its circumference, projections that extend over to the other coupling half. Arranged between the projections are tangential springs which, depending upon the applied moment of rotation, are more or less strongly compressed. In the case of torsionally elastic couplings, as are used for example between drive motors and the rollers of a steel rolling works, there is as yet no known auxiliary arrangement for protection against exceeding a predetermined maximum moment of rotation.